Circuit interrupters provide protection for electrical systems from electrical fault conditions, by way of example and not limitation, current overloads, short circuits, trip conditions and abnormal level voltage conditions. Typically, circuit interrupters include an operating mechanism which opens separable contacts to interrupt the current through the conductors of an electrical system in response to abnormal conditions.
Switching devices (e.g., circuit interrupters, circuit breakers, switches, reclosers) include separable contacts disposed within a housing. Generally, in a vacuum circuit interrupter, for example, contacts are fixed relative to both the housing and to an external electrical conductor which is interconnected with the circuit to be controlled by the circuit interrupter. A number of other contacts are moveable. A moveable contact assembly usually comprises a stem of circular cross-section having the moveable contact at one end and an operating mechanism at the other end. The fixed contact is electrically coupled to or in electric communication with the moveable contact in response to the operating mechanism when the contacts are closed to energize the electrical system. The fixed contact and the moveable contact are not electrically coupled when the contacts are open to de-energize the electrical system.
Dampening apparatuses typically use a dampening device to avoid having a circuit interrupter re-close its separable contacts, due to rebounding upon opening of the electrical system. It is known to employ air piston dampening elements coupled to circuit interrupters. The problem with air piston dampening elements is that the dampening elements are susceptible to air borne contamination, such as dust and dirt. This could result in a jammed dampening apparatus which could cause problems with the circuit interrupter by allowing the circuit interrupter to re-close its separable contacts in an energized position.
Accordingly, there is room for improvement in dampening apparatuses. There is also room for improvement in circuit interrupters including a dampening apparatus.